Electric fuse.



AL. W.Y DOWNES.

ELECTRIC EUsE.

APPLICATION FILED DBO. 15. 1903. l

Patented Jan. 12, 1909.

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UNITEDl l STATES Louis w. DowNis, oF. PROVIDENCE, RHODEISLAND, AssioNon To D & w

PATENT OFFICE.

PaoviDENoE, iinonii ISLAM), A'coijiionliTioN' orf Rhona' ISLAND.

sliecifiaaqz f' Leiters' Patent.

ELECTRIC FUSE:

Patented Jan. 12, 1,909.'

Application led December 15, 1903. Serial'No. 185,211.

To all'whom it 'may' cof/teem:

'the cover which' clos'es the/open( end of, the

Be it known that I, LOUIS W. DowNI-is, of Providence, Rhode Island, have invented a n ew and useful Electric Fuse, which invention isfully set forth in the following specification. i I lMy invention relates to inclosede fuses` of the plug type,. the lobject being to' provide means for indicating the 'condition ofthe I cup-like or hollow.4 plug-like in'closiiig cas ing and which cover i s"; exposed when the plug fuse is inserted in'i'ts socket oi" base,

the indicating means beiny thus visibleeven when tlie'fi'ise'v is in its s'oc t.' l

' pin, the shank of which p'as'se's invention will be "more fully eX- plainedfaind completely understood'in con'- n'ect'ion with the "accompanying drawings, wherein.;` I' l L' Figures 1 and 2 are vsectional views at' right-angles' to each other, of one embodiment of'th'e invention; Figsl 3""a`nd'4 are detail views of parts of the same; Fig.4 5` is a sectional 'ViewV and. Figf a'd'etail of another enibod'iinentaFigLV is' a'detail of a still other' embodiments. y

f Referring' to Figsgl and 2, 1 is a cuplike or hollow plu'g'casing, preferablycf porcelain, surrounded at' its' lower' end by a shell 2, preferably of spun brass rolled'to form a'sc'rew-threadon' Its'eXteriOr; shell 2 constitutes one of the socket-contacts onj'the plug casing.l

`-'ll'is the 'other socket-contact or terminal on 'the casing consisting ofi a headedfbolt or thro'uffh 'the end wall'ofpart 1." 'Whei'i'th'e plug use is screwedV into a'socket or basethe, contacts or terminals 2 and. 4, engage'correspordirig circuit terminals in the'socket, in a 'well-,known mannerf 'I l I.

''i's the main fuse wire or link connected at its lower` end to contact 4 'and'at its upper end `t a conductor 10,' shown in` the form of a flat strip, which isled Vdon'fnwardly through passage 9 in casing 1, and is electrically connected to sliell'2." The fuse link may (or may not) traverse an ai'r space in of removingl 569,373, OctoberA l,v 1896. As illustrated herein an air space 6 is formed by ,a capsule strung upon the fuse-link.- rllie cavity within the plug casing is filled by the usual non-conducting porous iilling 8. l A

lhe open eno. 0I the cup-like casing 1 is g closed by a cover consisting in this instance preferably fibrous. Uve coverl l14 L place a transparent disk '16 of mica, for example. Both tlie cover and disk 16 are securely lield iii place by a spun iiietal cap 3, open at its center and screw-threaded onto part 1'.

"7' is an auxiliary or indicatoi' fuse-link or greater electrical resistance than 'fuse-link, 5, electrically connected 'at one end to contact 4; "'.llie indicator wire 7 passes upwardly through lili'ing'b, outwardlythrougn open-V ing lo' in disk 11,'aiid downwardly through 3).' 'The openii'ig 56 thus formed is Il 'a'ge eiiought'o peiniitthe upper end oftlie indiby solder, to the conductor l0 at point' '.18'.

is forced back into' the opening 36 and xglued r cemented therein to securely close' the opei'iing. The part of the indicatorv wire which 'extends along the disk 11, passes over a countersu'nk recess o lde'piession 1-'1there- 17 is a small bodyof material 'located in recess- 14 a'n'd about the indicator wire 7'.

heated upon fusing of the indicator wire to sired indication' ofthe blowing of the fuse, preferably by discoloring', charring or lblack- 'ning a label, suchas hereinafter described, diie tothe heat developed by'` the burningof said material. f I' preferably employa paste composition ofordinaryl g'un -I powder.- dissolved in a waterisolution of' gum-arabic.' I however, employ a material,-wh'ich,' in the absence Aofaj label, will gire the 'desired indication by changefof appearan'cef-discol- 'ijation, charriii'g o'r blackening, for example. Diskv 11 'mayl or' may not be provided vwith vent' chenilles 13- i 1 'Theeinb'odiment of the invention shown in Figs. 5 and 6 is similar to that'of. Figs. 1 4, except for the following differences: The'open end' of the cup-like casing is 'closed may When this isetl'ected`tli'e plug'oi' pellet 12- `the manner set forth in my Batent. No.

of a disk 11, of non-conducting material,

wire, preferably of Grerinaii silver and of an opening 'in said disk forin'ed by puncn- 'i'i'ig out oi the saine a plug or pellet 'lz tr'ig.

c'atorwire to .'be' electrically connected, as

Said .material is adapted to be- |siilliciei'itly l '111e seconojoisk z2 placed over disk zu has 4a perioration at its center' over that portion o1 the nulle-.ttor w11'e 'l Whlch ,extends along the surlace orvdisk 2U; said perroration 1s lined with a material zal, similar to the matef rial/1( already described, which makes contact with tue wire 7. Mica disk zo may be placed over disk 22, the three disks zo, 22 and 25 beingrheld 1n place by cap lhe diskszu anu 2z are preterabiy hard tibrous material.

'l he operation is asfollows: Upon melting of tne main fuse l1nk by excess of current, a certain amount of current passes through indicator Wire 7, heating the same to a melting point. rlhe heat thus developed 'is suiticient to heat or ignite the gun-powder composition (17, Figs. 1 4 and 8, o1' 24, Figs'. 5 and 9), eii'ecting a change in the appearance of the plug tuseat th1s point in the manner above' indicated, and thereby af- `fording at the exterior of the cover what may be designated afspotindication of the condition of the main fuse-Wire.

'The disk of mica 16, Figs. 1, 2 and l8, or 23, Figs. 5 and -9 constitutes an outer exposed transparent covering over the gunpowder composition (or over the paper label V3l which covers said composition, when such label. is used) through which the indicated condition of the fuse may be observed at a glance. This covering` addsto the safety- `of the device, as any slight flash or dischargetrom the gn-powder-or other composition 1T, or from the burning of the label 31 .over saidcomposition, would be on the underside of\ said covering vor disk, and hence not exposed to the atmosphere or in the least dangerous as a source of fire. As will be appreciated, in certain localities the slightest flash or discharge from the fuse v would be extremely dangerous. Instead of being made of mica, the diskl or 23 may be'of any other suitable transparent material sufficiently non-inflammable andnoncombustible to withstand the heat generated by the burning of the material 17.

31. Fig. 7. is a label, such as above referred to. having imprinted thereon a small circle 32 and adapted to be placed Vover the gun# powder. composition orother material. In Fig. 8, this label is shown as applied to the construction of Figs. 1 to 4, being secured vto cover-1l by adhesive material with its .central part over the gun-powder Vconniosition' 17': the mica disk 1G is over-fthe label. 'In 'Fig'. 9 the label is applied to the construction of F ig. 5, being secured to disk 22 wessi by adhesive 'material with its central part over the gun-powder composition A24, and covered by mica disk 23.. Upon heating of the gun-powder composition the desired indication is afforded by the production of a discolored, charred, or blackened spot on the label,-or in some cases incidentally burning a hole in the label,-at or within the circle 32. lThe arrangement may be such as to developsuiiicient heat to actually burn a hole through (at the same time discoloring or` blackening) the label, but I prefer to avoid all llame and to simply char, blacken or discolor the label.

From the above. description it will be understood that I provide 'at lthe exposed or outer end or part of the incloscd plug fuse (meaning thereby that part which is not obscured from view when the plug fuse is inserted in a socket) means for giving a visual indication of the condition ot the fuse.

As is apparent from the several embodiments shown, my invention is capable of various mechanical expressions and 1s notrestricted to details of construction.

What I claim is:

1. In a plug-fuse, a cup-like or hollow plug casing; a main fuse-wire inclosed by the casing; a cover closing the open end-of the casing; an auxiliary or .in'dicatorfnse-vv 95 wire also incloscd by said casing and in parallel circuit with the mainv fuse-wire, said indicator wire being associated with said cover and adapted to afford at the exterior ofthe cover a visual indication of the condi'- tion of said main fuse-wire; and an annular cap removably securing the cover on vthe casing.

2. In a plug-fuse, a cup-'like or hollow plug casing; a main fiise-wire incloscd by the casing; a cover closing the open end of the casing; indicatingmeans including an auxiliary or indicator fuse-wire in parallel circuit with the main fuse-wire, and a small body' of suitable combustible material associated with-the cover and indicator wire and adapted upon fusingof said indicator Wire to afford at the exterior of the cover a visual indication of the condition of the main fusewire; and an outer transparent suitably noncombustible covering applied to the cover over the indicatinV means.

3. In an inclose electric fuse of plug type, a casing comprising a hollow member and two disks closing the outer open end thereof; a main fuse-link within the casing; and an auxiliary or indicating `fuse-link 'or -wire within the casing having a part passing between the disks.

4. In an incloscd electric fuse of plug type, a casing comprising a hollow member and two disks closing the outer open end thereof, the outer disk having an opening therein; a main fuse-link within the casing: an auxiliary or indicating fse-link or wire within the casing and having a part passing ber tween the disks and under the opening in .ing

the outer disk; and a material in said o ening and in contact with the auxiliary uselink and adapted upon disruption of the main fuse-link to he heated by the auxiliary fuse-link to effect a visual indication of said disruption.

5. In an inclosed electric fuse of plug type, a. casing comprising a hollow member and two disks closing the outer open end thereof,

the ,outer disk having an opening therein; a' main fuse-link within the casing; an auxiliary or indicating fuselink or wire within thecasing and having a part passing between the disks and undery the` opening in the outer disk; and a material in said openand in contact with the auxiliary fuselink and adapted upon disruption of the main fuse-link to be heated by theauxiliary fuse-link to effect a visual indication of said and an outermost transparent disruption;

through which said indicadisk or covering tion is visible.

6. A plug fuse having a hollow base open at one end, metallic contacts thereon, main and indicator Wires connecting said contacts, an insulating disk over the open end of said base and provided With apertures through which the indicator wire is threaded, a disk of transparent material located outside said insulating disk, and a centrally apertured cap engaging the sides of said base and clamping the Said disks between its inner surface and the end of the base.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

1 LOUIS W. DOWNES. Witnesses: NVM. C. WooDwARD, W. S.'SUssoN. 

